Sensitivity amplification strategy by implementing click chemistry in the construction of biosensing interface can efficiently improve the performance of immunosensor. Herein, we developed a sandwich-type amperometric immunosensor for ultrasensitive detection of carbohydrate antigen 24-2 (CA 242) based on pH responsive label-assisted click chemistry triggered sensitivity amplification strategy. The sensitivity of amperometric immunosensor relies on the current response differences (ΔI) caused by per unit concentration target analyte. The pH responsive Cu²⁺-loaded polydopamine (CuPDA) particles conjugated with detection antibodies were employed as labels, which can release Cu(II) ions by regulating pH. In the presence of ascorbic acid (reductant), Cu(II) ions were reduced to Cu(I) ions. Azide-functionalized double-stranded DNA (dsDNA) as signal enhancer was immobilized on the substrate through Cu⁺-catalyzed azide/alkyne cycloaddition reaction. With the help of the click reaction, the ΔI caused by target was elevated prominently, resulting in sensitivity amplification of the immunosensor. Under optimal condition, the proposed immunosensor exhibited excellent performance with linear range from 0.0001 to 100 U mL⁻¹ and ultralow detection limit of 20.74 μU mL⁻¹. This work successfully combines click chemistry with pH-responsive labels in sandwich-type amperometric immunosensor, providing a promising sensitivity amplification strategy to construct immunosensing platform for analysis of other tumor marker.

通过在生物传感界面的构建中实施点击化学的灵敏度放大策略，可以有效提高免疫传感器的性能。在这里，我们开发了一种三明治型安培型免疫传感器，用于基于pH响应标签辅助点击化学触发的灵敏度扩增策略的碳水化合物抗原24-2（CA 242）的超灵敏检测。电流型免疫传感器的灵敏度取决于单位浓度的目标分析物引起的电流响应差异（ΔI）。pH响应性Cu ²⁺载有检测抗体的聚多巴胺（CuPDA）颗粒被用作标记，可通过调节pH值释放Cu（II）离子。在抗坏血酸（还原剂）存在下，Cu（II）离子被还原为Cu（I）离子。通过Cu ⁺催化的叠氮化物/炔烃环加成反应，将叠氮化物官能化的双链DNA（dsDNA）作为信号增强剂固定在基质上。借助于点击反应，由靶标引起的ΔI显着升高，导致免疫传感器的灵敏度增强。在最佳条件下，拟议的免疫传感器表现出出色的性能，线性范围为0.0001至100 U mL ^-1，超低检测限为20.74μUmL ^-1。这项工作成功地将点击化学与pH响应标记物结合在夹心型电流型免疫传感器中，为构建用于分析其他肿瘤标记物的免疫传感平台提供了一种有前途的灵敏度扩增策略。